WWiSE Words on 802.11n
By Eric Griffith

As the last IEEE 802 Working Group (WG) meeting was taking place in July, Agere Systems came out swinging, ready to talk about why its proposal for the future 802.11n high-speed wireless standard -- backed by companies like Atheros and Intel, all under the name TGn Sync -- was the one to beat.

At the time, the other camp, known as WWiSE, for "World-Wide Spectrum Efficiency," wasn't ready to say much about its proposal. However, since all the initial 802.11n proposals both large and small are due to be available on the IEEE's servers by this weekend, the WWiSE consortium have decided to unveil the specifics of what they hope will be the next standard. The companies that formed WWiSE are all chip makers: Airgo Networks, Bermai, Broadcom, Conexant Systems, STMicroelectronics and Texas Instruments (TI).

Standard ala WWiSE

Jim Zyren, Conexant's director of strategic marketing, was part of a conference call today with analysts and reporters during which they presented the WWiSE proposal. It will consist of both Physical (PHY) and Media Access Control (MAC) Layer enhancements, both mandatory -- those required to get the throughput above 100Mbps, as chartered by the 802.11n Task Group -- and some optional for extra enhancements.

"Both [mandatory and optional elements] are important to the industry," says Zyren. "Take, for example, 802.11g. Mandatory there is only speed of 24 Megabits per second (Mbps). But the optional elements go up to 54Mbps." That higher speed is considered the standard today, and is required in testing for Wi-Fi Certification by the Wi-Fi Alliance.

A key aspect of the WWiSE proposal is use of 20MHz channels as mandatory. They feel that this way they comply with regulatory domains around the world today, including Japan, which has more stringent rules than others. "The implementation doesn't anticipate future regulatory changes," says Zyren.

Also mandatory would be the use of MIMO-OFDM technology in a 2x2 configuration -- two antennas for receiving on one end of the signal, and two for transmitting from the other end. With this, they expect to have a maximum data rate of 135Mbps on a single 20MHz channel.

While WWiSE is sticking with 20MHz for mandatory use, they propose the option of 40MHz channels where permitted (so not in Japan, for example). Couple this with a 4x4 MIMO configuration, and they say data rates could shoot to 540Mbps.

Dr. Sean Coffey, manager of the Advanced Technology Group WLAN at TI, says that backwards compatibility is another reason to stay with the 20MHz channels as mandatory, so 802.11n products can handle talking to the "legacy" 802.11a/b/g equipment.

The Other Group

How does this differ from what TGn Sync will propose? From what Agere said in July, not much -- only in that TGn Sync thinks that 40MHz channels should be mandatory, then dummy back to 20MHz when used with legacy systems. At the time, Agere strategic marketing manager Mary Cramer said, "You can't cripple the standard for one country."

The WWiSE group says at this time that it doesn't know anything specific about the TGn Sync proposals, and wouldn't want to compare or contrast the proposals until they're available officially this weekend.

This is all a very early stage to be even talking about the specifics of a high-speed standard -- 802.11n's spec probably won't be agreed upon for another year, and probably won't be finalized until early 2007. Zyren admitted that, saying, "There's no guarantee that the work we're preparing here won't come to naught. There's a long process ahead of us."

No Charge for the IP

Despite the IEEE's focus on its members as individual people, they all work for corporations, and corporations know it's never too early to try and grab some mindshare.

As corporations, however, the companies behind these proposals have more to offer than just personnel in meetings -- they have intellectual property (IP) and patents to protect. And when working with a standards body, sometimes that IP will have to be used for the good of the standard. So WWiSE went out of its way to say that all of the companies involved would offer their IP under the terms of RAND (Reasonable and Non-Discriminatory) licensing, so WWiSE will offer reciprocal licensing (RAND-Z, for "zero royalty") to all who use the final technology. No charge will be made to developers who want to use 802.11n based on the WWiSE proposal. This isn't a big surprise, as RAND is required by the IEEE for all proposals -- they don't want lawsuits gumming up the works. [Zyren clarified after this story went to press that while the IEEE expects RAND letters from proposing companies, RAND-Z is not required, and that offering zero-royalty access is a step above and beyond. He also reminded that such matters have led to previous lawsuits, specifically Agere suing Intersil (whose Wi-Fi IP is know owned by Conexant) in 2002 over patent infringement over IP in the 802.11b specification. Intersil counter-sued. The suit, filed in United States District Court in Delaware, is ongoing but Zyren couldn't comment on the merits of the case.]

It's interesting that Agere/TGn Sync's Cramer had said previously that she felt the WWiSE proposal didn't meet the requirements for RAND-Z, when arguably the biggest bit of IP offered by both groups is probably owned by WWiSE member Airgo Networks. That tech is MIMO-OFDM, the ability to send multiple bits of data on the same channel.

All the IP stuff probably won't matter in the long run -- since both proposals include the use of MIMO and they'll likely have to compromise toward a single standard anyway, they'll all end up working with Airgo in the end. In theory, at least... fights between the groups trying to create an ultrawideband standard in 802.15.3a caused a split in the group that remains in place today. No one is expecting that within the 802.11n Task Group.

The 11n proposals will be officially presented in Berlin, Germany next month at the next 802 WG meeting, and debate over what proposal is best will begin in earnest at the November meeting.

August 12, 2004